1. Field of the Invention
The present invention relates to a liquid discharge head unit used for a liquid discharge apparatus that performs recording operation by discharging liquid, such as ink, from discharge ports in the form of liquid droplets. The invention also relates to a head cartridge and a method for manufacturing a liquid discharge head unit as well. In this respect, the liquid discharge head unit of the invention is applicable to a copying machine, a facsimile equipment having communication systems, a word processor having a printing unit, besides a printing apparatus generally used. Further, the invention is applicable to a recording system for industrial use which is provided with various kinds of processing apparatuses complexly combined therein.
2. Related Background Art
The liquid discharge apparatus (ink jet recording apparatus) is a recording apparatus of the so-called non-impact recording type, which makes it possible to record on various kinds of recording mediums at high speed. With the advantages such as to make almost no noises in printing, the liquid discharge apparatus is widely adopted for a printer, a copying machine, a facsimile equipment, a word processor, or the like that carries a recording mechanism.
As the typical liquid discharge method for a liquid discharge head to be mounted on a liquid discharge apparatus of the kind, there have been known the one that uses electromechanical converting device, such as piezo-element; the one that uses the irradiation of laser or other electromagnetic waves in order to discharge liquid droplets by the heating thereof; or the one that discharges liquid droplets by the action of film boiling generated by heat given to liquid by use of electrothermal converting devices (heaters) each having a heating resistive element therefor. The liquid discharge head, which uses electrothermal converting devices as discharge energy generating elements, is provided with electrothermal converting devices arranged in the liquid flow paths, respectively, and when electric pulses are applied to them for generating heat, thermal energy is given to ink. By the utilization of the bubbling pressure of liquid at the time of bubbling (boiling) exerted by the phaseal changes of liquid then, fine liquid droplets are discharged from fine discharge ports to record on a recording medium. In general, the liquid discharge head comprises discharge ports for discharging liquid droplets, and a supply system for supplying ink to these discharge ports.
The liquid discharge apparatus that uses the electrothermal converting devices described above has advantages in that it is relatively easy to perform image recording in high image quality and in high precision, and also, relatively easy to arrange the structure whereby to record images in colors. While the liquid discharge apparatus of the kind is being manufactured, it is demanded more to make the recording apparatus itself smaller. To meet such demand, there is used a head cartridge which is integrally formed compactly by a liquid discharge head and a liquid retaining portion that retains liquid to be supplied to the head.
The head cartridge of the kind may be provided with a liquid retaining portion capable of retaining ink of plural colors for the formation of color image or with a liquid retaining portion having liquid containers arranged to be exchangeable when ink has been consumed in order to reduce the running costs thereof. Also, it is known to use the liquid discharge head chip as a liquid discharge head which is compactly structured by bonding an orifice plate having discharge ports formed therefor to an element base plate having fine heaters, liquid flow paths, and others formed thereon. Then, this liquid discharge head chip is incorporated in the liquid discharge head unit provided with means for holding the chip in a designated position, and liquid supply means for conducting liquid from the liquid retaining portion to the liquid discharge head, among some others. This unit is bonded to the liquid retaining portion to structure a head cartridge unit. The liquid discharge head unit used for color image recording has a plurality of liquid discharge head chips incorporated in order to discharge ink of each color. Also, there may be a plurality of liquid discharge head chips incorporated in the liquid discharge head unit for the purpose of speeding up the recording operation.
However, for the liquid discharge head unit of the kind, it is required to position the liquid discharge head chip, the position of the discharge ports in particular, in high precision with respect to the liquid discharge apparatus main body so that liquid can be discharged to the appropriate positions for recording highly precise images.
Also, when the liquid discharge head unit is bonded to the liquid retaining portion or when the head unit is installed on the liquid discharge apparatus main body, there is a fear that the orifice plate is caused to be deformed or present some other defects if external force is given to the liquid discharge port formation surface, thus producing unfavorable effect on the preciseness of liquid discharges.
Therefore, the present invention aims at the provision of a liquid discharge head unit capable of positioning the discharge ports to a liquid discharge apparatus main body in high precision for executing highly precise liquid discharges, and also, aims at the provision of a head cartridge, as well as a method for manufacturing such liquid discharge head unit.
Also, it is another object of the present invention to provide a liquid discharge head unit capable of preventing external force from being exerted on the liquid discharge formation surface in order to avoid producing adverse effect on the preciseness of liquid discharges, and also, to provide a head cartridge, as well as a method for manufacturing such liquid discharge head unit.
In order to achieve these objects, the liquid discharge head unit of the present invention comprises a base plate having the installation reference used as positioning reference for the installation thereof on a liquid discharge apparatus main body; a frame connected to the base plate, having liquid supply paths formed therein for conducting liquid, and liquid supply ports communicated with the liquid supply paths open to side portion; a chip unit provided with discharge energy generating elements for heating the liquid to be bubbled and discharged, discharge ports for discharging the liquid, and liquid receiving ports for receiving the liquid into the interior thereof, and connected to the frame in a state of abutting against the side portion of the frame so as to enable the liquid supply ports and the liquid receiving ports to be communicated; and a front cap having opening portion to enable the discharge ports to be exposed to the outside, being arranged to cover the chip unit and the frame by covering at least the surface having the discharge ports open thereto, and connected to the chip unit and the frame.
With the structure thus arranged, the frame abuts against the base plate to be connected to the base plate in a state where the frame is in the relative positions designated for the installation reference, and further, the chip unit can abut against the side portion of this frame to be connected to the frame in a state of being in the relative positions designated for the installation reference, hence making it easier to position the discharge ports open to the chip unit in high precision with respect to the installation reference. Consequently, the position of the discharge ports can be arranged in high precision with respect to the liquid discharge apparatus main body to make it possible to structure a liquid discharge head unit capable of executing highly precise liquid discharges.
Also, with the provision of the front cap, it becomes possible to protect the liquid discharge surface from the external force that may be exerted on the discharge port formation surface, and avoid the adverse effect that may be produced by external force on the preciseness of liquid discharges. For the front cap, too, it is easier to make connection in a state of being in the relative positions designated for the installation reference. In this way, the front cap is prevented from being in contact with a recording medium.
The liquid discharge head is characterized in that the frame, the chip unit, and the front cap are arranged in relative positions designated for the installation reference.
If the frame is connected with the base plate by use of screws, it becomes possible to remove the screws and arrange the face again for connection in a case where the installation reference and the relative positions are found to be deviated after the frame has been connected. In this manner, these can be positioned and connected in higher precision.
If the frame is formed by ceramic, it becomes possible to perform a highly precise machining accompanied by process heating, because ceramic has a small thermal expansion. The abutting surface, the installation referential surface, and the like for the base plate and chip unit can be processed with high surface precision to enable each member to be arranged in high precision. Also, it becomes possible to prevent the frame from being deformed, thus suppressing the positional displacement of discharge ports due to heat or the like generated by driving discharge energy generating elements.
Also, it is possible to effectively obtain a protective function not to exert external force on the discharge port formation surface by positioning the surface of the front cap having the opening portion open thereto more in front in the direction of the liquid discharges than the surface of the chip unit having the discharge ports open thereto.
Further, in the case where the chip unit is provided with a flat type orifice plate having the discharge ports open thereto, which is connected to the other portions of the chip unit, if the size of the opening portion is smaller than the size of the orifice plate, and the front cap covers the upper side portion of the orifice plate, it becomes possible to prevent the orifice plate from being peeled off by not allowing any force to be exerted on the side portion of the orifice plate when liquid (ink) or the like adhering to the liquid discharge surface is removed by use of a blade.
It is possible to bond the front cap on the designated position easily by arranging, on the side face portions of the surface of the front cap having the opening portion open thereto, holes for use of UV bonding agent with narrower portions formed on the way near the front edge portions thereof and extended forwardly from the rear edge portion of the frame in the direction toward the surface having the opening portion open thereto, and by coating UV bonding agent on the portions having the parts more in front than the narrower portions of the holes for use of bonding agent positioned on the side face portions of the frame, before the front cap is arranged on the designated position, and subsequently, arranging the front cap on the designated position for hardening the UV agent by the irradiation of UV rays through the holes for use of bonding agent. Also, since the UV agent is hardened inside the portion more in front than the narrower portion of the hole for use of bonding agent, it is made possible to keep the front cap firmly stationary even if a load is given in the direction perpendicular to the surface having the opening portion open thereto, because the hardened bonding agent stays on the edge of the hole for use of bonding agent.
It is preferable to give a water repellent treatment to the surface of the front cap having the opening portion open thereto so that any discharged liquid that may adhere does not flow to the liquid discharge ports to exert influence on the preciseness of liquid discharges. Particularly, it is preferable to give such repellent treatment by means of Teflon coating. In accordance with the present invention, various kinds of materials can be used for the manufacture of the front cap. Therefore, it is possible to exercise the Teflon coating that needs baking process.
The head cartridge of the present invention comprises a liquid discharge head unit referred to in the preceding paragraphs, and a liquid container portion for containing liquid to be supplied to the liquid discharge head unit.
The method of the present invention for manufacturing a liquid discharge head unit comprises the following steps of:
manufacturing a base plate having the installation reference used as positioning reference for the installation thereof on a liquid discharge apparatus main body, and
a frame connected to the base plate, having liquid supply paths formed therein for conducting liquid, and liquid supply ports communicated with the liquid supply paths open to side portion;
connecting the frame in the state of abutting against the base plate and being arranged in the relative positions designated for the installation reference;
manufacturing a chip unit provided with discharge energy generating elements for heating liquid to be bubbled and discharged, discharge ports for discharging the liquid, and liquid receiving ports for receiving the liquid into the interior thereof;
connecting the frame in a state of abutting against the side portion of the frame to enable the liquid supply ports and the liquid receiving ports to be communicated;
manufacturing a front cap having opening portion to enable the discharge ports to be exposed to the outside, being configured to cover the chip unit and the frame by covering at least the surface having the discharge ports open thereto; and
connecting the front cap to the chip unit and the frame in a state of covering the chip unit and the frame and being arranged to be in the relative positions designated for the installation reference.
Further, this method of manufacture is characterized in comprising the following steps of:
coating UV bonding agent, before the front cap is arranged on the designated position, on the portions of the side faces of the frame having each portion more in front of the narrower portion of the hole for use of the bonding agent at the time of being arranged on the designated position by use of the front cap provided with the hole for use of the bonding agent on the face on the side of the surface having the opening portion open thereto, being extended from the rear edge portion forwardly in the direction toward the surface having the opening portion open thereto, and having the narrower portion on the way near the front edge portion thereof;
arranging the front cap after the coating on the designated position; and
irradiating after the arrangement ultraviolet rays to the UV bonding to be hardened through the hole for use of UV bonding agent.
Also, the liquid discharge head unit in accordance with another embodiment of the present invention, which is provided with a supporting member having an installation reference used for the positioning reference for the installation on a liquid discharge apparatus main body, liquid supply paths formed inside for conducting liquid, liquid supply ports communicated with the liquid supply paths, being open to the side portion; and a chip unit having discharge energy generating elements for heating the liquid to be bubbled and discharged, discharge ports for discharging the liquid, and liquid receiving ports for receiving the liquid into the inside thereof, the liquid supply ports and the liquid receiving ports being connected to be communicated in a state of abutting against the side portion of the supporting member, comprises a front cap having an opening portion to enable the discharge ports to be exposed to the outside, being arranged to cover the chip unit and the supporting member by covering at least the surface having the discharge ports open thereto, and connected to the chip unit and the supporting member, in which the chip unit is provided with a flat type orifice plate, having the discharge ports open thereto, connected to the other portion of the chip unit, and the size of the opening portion is smaller than the size of the orifice plate, and the front cap covers above the side portions of the orifice plate.
In other words, the liquid discharge head unit of the present invention is characterized particularly in that the front cap is provided to cover above the side portion of the orifice plate, whereby to obtain the function to protect the orifice plate. Therefore, the preferable structure of the front cap installation is not necessarily the one having the base pate and the frame. The structure may be formed with the provision of the chip unit and the supporting member therefor.
In this case, too, it is preferable to arrange the chip unit and the front cap in the relative positions designated for the installation reference, because with such arrangement, the precision of liquid discharges can be enhanced, and the function to protect the front cap can be obtained in a better condition.
Also, it is preferable to position the surface of the front cap having the opening portion open thereto more in front in the discharging direction of the liquid than the surface of the chip unit having the discharge ports open thereto, because with this positioning, the orifice plate can be protected effectively.
Also, it is preferable to arrange, on the side face portions of the surface of the front cap having the opening open thereto, holes for use of UV bonding agent with narrower portions formed on the way near the front edge portions, and extended forwardly from the rear edge portion of the frame in the direction toward the surface having the opening portion open thereto, and to coat and harden UV bonding agent is on the portions having the parts more in front than the narrower portions of the holes for use of bonding agent positioned on the side face portions of the frame, because, in this way, the front cap can be arranged and fixed in high precision, particularly firmly fixed with ease so as not to allow the position to deviate forward and backward in the liquid discharging direction.
Also, it is preferable to give a water treatment to the surface of the front cap having the opening portion open thereto by means of Teflon-coating in particular, because with this treatment, the adhesion of liquid to the discharge surface can be avoided.
The head cartridge in this case is characterized in that it comprises a liquid discharge head unit thus structured, and a liquid containing portion for containing the liquid to be supplied to the liquid discharge head unit.
Also, the method for manufacturing a liquid discharge head unit in this case comprises the following steps of:
manufacturing a supporting member provided with an installation reference used for the positioning reference for the installation on a liquid discharge apparatus main body, liquid supply paths formed inside for conducting liquid, liquid supply ports communicated with the liquid supply paths, being open to the side portion;
manufacturing a chip unit provided with discharge energy generating elements for heating the liquid to be bubbled and discharged, discharge ports for discharging the liquid, and liquid receiving ports for receiving the liquid into the inside thereof;
connecting the chip unit to the supporting member in a state of abutting against the side portion of the supporting member to enable the liquid supply ports and the liquid receiving ports to be communicated, and arranging to be in the relative positions designated for the installation reference;
manufacturing a front cap having an opening portion to enable the discharge ports to be exposed to the outside, being configured to cover the chip unit and the supporting member by covering at least the surface having the discharge ports open thereto; and
connecting the front cap to the chip unit and the supporting member in a state of covering the chip unit and the supporting member, and being arranged to be in the relative positions designated for the installation reference.
Further, this method comprises the following steps of:
coating UV bonding agent, before the front cap is arranged on the designated position, on the portions of the side faces of the frame having each portion more in front of the narrower portion of the hole for use of the bonding agent at the time of being arranged on the designated position by use of the front cap provided with the hole for use of the bonding agent on the face on the side of the surface having the opening portion open thereto, being extended from the rear edge portion forwardly in the direction toward the surface having the opening portion open thereto, and having the narrower portion on the way near the front edge portion thereof;
arranging the front cap, after this coating, on the designated position; and
irradiating, after this arrangement, ultraviolet rays to the UV bonding to be hardened through the hole for use of UV bonding agent.